This application claims the benefit of German patent application DE P 10040109.0 filed Aug. 17, 2000, herein incorporated by reference.
The present invention relates to a bearing housing for a drive device for a creel of a cheese-producing textile machine and, more particularly, to such a bearing housing for an electromotor drive device which is integrated into the creel and can be loaded or charged with a braking current counter to the nominal rated current of the drive device for braking the cheese.
Drive devices which are arranged on the creel are known in particular in connection with bobbin winding devices which were developed for producing cheeses of the xe2x80x9cprecision windingxe2x80x9d, or xe2x80x9cstepped precision windingxe2x80x9d types.
Subsequently published German Patent Publication DE 199 08 093.3, for example, describes a bobbin winding device in which a cheese held in a creel is directly driven by a drive motor integrated into the creel. The cheese rests on a pressure roller that is not driven itself. Traversing of the yarn to be wound takes place by means of a finger-like yarn guide operated by a separate drive. The two drives can be controlled via an appropriate control device such that a defined, pre-selectable winding ratio is always obtained.
Since it is necessary to stop a cheese frequently in the course of the overall process of winding yarn onto the cheese, for example, when a yarn supply cop is exhausted, upon a yarn break, or following a controlled cutting of the yarn via a yarn cleaner, the known winding device also comprises a pneumatically loadable braking device integrated into the creel. This known braking device is comprised of a brake lining fixed on the stator housing of the electromotor to rotate in unison with the housing, against which a contact surface of a tube receiving plate, embodied as a brake disk, can be pneumatically pressed. The braking force thereby produced rapidly brings the cheese to a stop.
However, this known cheese winding device has a number of disadvantages which have prevented the device from becoming accepted in actual use. Both the rotating brake disk and the stationary brake lining are subjected to significant wear and therefore the braking device requires intensive maintenance. In addition, the brake dust created can readily enter into the axial sliding guide of the cheese drive as well as into the bearing of the electromotor and considerably hampers the functioning or may even cause breakdown of these components.
Other cheese winding devices are known, for example from German Patent Publication DE 198 36 701 A1, in which a grooved drum that drives the cheese and at the same time traverses the yarn is electrically braked to a standstill after the cheese has been lifted off. To this end, the drive motor of the grooved drum is loaded or charged with a braking current that is usually a multiple of the nominal rated current of the drive motor. In the process, the drive motors of such cheese winding devices are subjected to considerable loads, especially when large cheeses must be repeatedly braked and accelerated at short time intervals. For this reason, the dimensions of the drive motors are made quite large, in particular for preventing overheating, and as a rule are correspondingly heavy.
It is known from German Patent Publications DE 21 06 898 A1 or German Patent DD 214,114 that textile machine drive devices which are subjected to large thermal loads can be provided with cooling ribs so that the motor heat can be removed via convection and radiation into the ambient environment. Alternatively, as described in German Patent DE 27 14 299 C2, such drive devices can be cooled by a permanent application of compressed air.
As already mentioned above, these known drive devices are comparatively large, bulky and heavy, especially when correspondingly large output data are demanded. However, drive devices which are intended to be integrated directly into the creel of a cheese-producing textile machine must be as small and lightweight as possible, since during the winding process their weight results in an additional unwanted load on the rotation of the cheese on the associated pressure roller.
Such relatively small drive devices are correspondingly greatly stressed during operation. Thus, the motors often become very hot, including the area of their motor housing. Accordingly, in the interest of promoting sufficient cooling, the motor housing is arranged to be exposed to the ambient environment, but as a result the unintentional touching of this component by the machine operators cannot always be avoided. Therefore there is the constant danger of the operators being injured by burns from these components.
In view of the above described state of the art, the present invention seeks to address the problem of providing a bearing housing for a drive device integrated in a creel which, on the one hand, permits sufficient cooling of the drive device and, on the other hand, minimizes the danger of injuries to the operators.
The present invention is addressed by providing a bearing housing for a drive device integrated in a creel of a cheese-producing textile machine, wherein the drive device is loadable with a braking current counter to the nominal rated current of the drive device for braking the cheese. In accordance with the present invention, the bearing housing comprises a plurality of cooling ribs each having an exterior covered with a material having a low heat conductivity.
This design of the bearing housing in accordance with the present invention assures that, by insulating the areas of accessible cooling ribs with a material of poor heat conductivity, these danger areas for the operators are defused. Accordingly, it is assured that the outer areas of the cooling ribs can no longer become so hot, even at extremely high motor temperatures, that there would be a danger of being burned by these components.
Because of the defusing of the critical bearing housing area, the drive devices can be operated at higher motor temperatures. The surface temperature in the lower, uncovered cooling rib areas of the bearing housing rises because of the increased motor heat of the drive devices, which results in a clearly increased heat transfer to the surroundings in these areas.
Thus, the present invention has the advantage that, in spite of a reduction of the cooling surface of the bearing housing, its cooling output is increased, and in the process the danger of injuries to the operators is simultaneously minimized.
In a preferred design, the caps of the cooling ribs of the bearing housing are made of a thermoplastic material, preferably polyamide. Since the heat conductivity of such a material is considerably less than the heat conductivity of, for example steel or aluminum, the cooling ribs in the areas in which they are accessible to the operators remain below a level critical for the operators, even at high motor temperatures. Thus, in their accessible areas the cooling ribs never become so hot that the danger of burning arises for the operators.
It is further preferred that the mutual spacing between the cooling ribs is selected to be such that an unintentional access to the unprotected intermediate hot portions of the cooling ribs is dependably prevented.
In a further alternative design, a sensor device is arranged in the area of the bearing housing. Such a sensor device allows the permanent monitoring of the existing bearing housing temperature and, when utilized in connection with an auxiliary cooling device, a directed intervention may be actuated if a critical motor temperature of the drive device should be reached.
In a preferred embodiment, the auxiliary cooling device, for example may be a compressed air device installed in the area of the bearing housing. This compressed air device, which can be activated as a result of an appropriate signal from the sensor device, can be temporarily connected with a compressed air source via a valve when the drive device has reached a critical temperature level. Thus, the auxiliary cooling device is actuated only under exceptional circumstances; under normal operations, the motor heat can be carried off via the cooling ribs by means of convection and radiation.
Further details, features and advantages of the present invention will be described and understood from an exemplary embodiment which is described hereinbelow with reference to the accompanying drawings.